SkiaSharp has some MAUI integration, but AFAIK it's not used to render things. At least not when I last looked. On most (all?) platforms native drawing methods are used (which fits well into how MAUI works on each platform, admittedly). This comes with the drawback that performance varies wildly across platforms, however. (NB: I've last looked deeply into MAUI about a year ago, so things may have changed.)

MAUI renders by wrapping the native UI components on whatever platform (UIKit, Jetpack, etc). It doesn't use Skia for drawing.